Hubert H. Humphrey's last legislation initiative, a sweeping proposal to reorganize the American foreign aid program, was introduced in the Senate yesterday.

The proposal would abolish the Agency for International Development, incorporating its functions and those of amny other government agencies involved in bilateral and multilateral foreign assistance into a new International Development Cooperation Administration (IDCA).

This agency would be independent of the State Department, and its administrator would report directly to the president. It would absorb the Peace Corps, now part of ACTION, and sections of the Treasury Department now engaged in multilateral foreign assistance issues.

Humphrey completed work on a speech he hoped to make introducing the bill just two days before he died. It was a classic piece of Humphrey rhetoric:

"Demand for change - yes, fundamental and radical change [in the way the U.S. administers foreign aid] - has been coming. It is like a gathering storm, and it has now arrived in all its fury."

He predicted that "the balance of this century will continue to be a period of incredible, massive change in political, economic and social institutions," and said the United States would have to take the initiative "to affect and move this global upheaval."

Humphrey's bill was introduced yesterday by Sens. Clifford P. Case (R-N.J.) and John Sparkman (D-Ala.), Sparkman, the Foreign Relations Committee chairman, called the measure "a living monument to our dear friend."

The Carter administration reserved its position on the proposed legislation. A White House spokesman said last night that the bill was "constructive and serious, and we'll consider it carefully."

The administration may have trouble endorsing the legislation because it incorporates numerous explicit policy guidelines as congressional mandates to the executive branch.

On the other hand, the Humphrey proposal appears to concide with the administration's interest in pragmatic reorganization intended to streamline government.

Sources at the Agency for Internatioanl Development speculated that the professional staff there would probably endorse the Humphrey proposal, since it would strengthen the organization of foreign and administration and also signal increased American interest in the fate of developing countries.

One provision in the proposed bill would abolish the dual personnel system within aid - a combination of the Foreign Service and Civil Service - replacing it with a new corps of "international development officers."

The draft bill covers 159 pages and covers an enormous amount of political and legislative territory. Among its provision are these:

Sweeping instructions to the executive branch, telling it in effect how to administer a foreign aid program, in some cases specifying the amount of money to be given to individual countries.

A theme of the bill is that the poorest countries deserve the most attention. The legislation suggests that the United States partially forgive the debts of the very poorest countries, provided they invest the money they owe the United States in approved development projects.

Authorization for a new "International Development Institute" within the proposed IDCA to oversee the Peace Corps and help coordinate the activities of private groups and volunteer organizations that contribute to foreign assistance efforts.

Hearings on the legisaltion are scheduled to begin on Feb. 27 in a subcommittee chaired by Sparkman. Staff aides who worked on drafting the legislation said they expect it will have to be refined substanially before it can be passed into law.